A mashing method as described above is disclosed in British patent GB-B 879 470. More specifically, said British patent describes a continuous method for the production of brewer's wort wherein heat-treated mash is introduced onto a first screen separator. The spent grains passing off the first screen separator drop into a first wash vessel where they are met and mixed with a very dilute wort originating from the screen separation of a grain slurry of a second wash vessel. The mixed slurry in the first wash vessel overflows onto a second screen separator. The dilute wort passing through the second screen separator is recirculated to the mashing step and the spent grains passing off the screen drop into the second wash-vessel where it is combined with a water stream. The slurry in second wash vessel overflows onto a third screen separator. The very dilute wort passing through the screen is pumped to the first wash vessel and the spent grains discharged from the screen go to spent grain disposal.
The method described in the British patent comprises continuously subjecting the solids fraction to counter-current extraction in a plurality of stages, each of which stages comprises reslurrying with wash effluent from a succeeding stage and mechanical separation of the coarse solids, to produce a substantially fully exhausted coarse solids waste. The examples of the British patent describe the results of three different production runs. The process wort streams produced in these runs had a specific gravity (S.G.) in the range of 1.04117 to 1.04484. These specific gravities equate to a gravity of about 10-11 degrees Plato (° P).
German patent application DE-A 42 44 596 describes a process for the production of alcohol free beer, wherein solid-liquid separation is achieved in a continuous fashion in a sequence of three decanters. Heat treated mash is introduced in a first decanter where it is separated in process wort and spent grain. The spent grain from the first decanter is transferred to a second decanter in which it is combined with dilute wort obtained from a third decanter. The dilute wort obtained from the second decanter is recirculated to the mashing step. The spent grain obtained from the second decanter is transferred to a third decanter in which it is combined with water. The exhausted spent grain obtained from the third decanter is discarded.
In the prior art beer brewing processes have been described that comprise the preparation of a high gravity mash extract. U.S. Pat. No. 4,140,799 describes a batch process for the preparation of an alcoholic beverage, comprising the steps of preparing an aqueous fermentable substrate containing fermentable carbohydrates and having a solids content in the range of 18° to 36° Plato. It is stated in the US patent that, in general, the wort is prepared by mashing malt with an adjunct, with the malt comprising from about 35% to 65% by weight of the total extract weight. The US patent teaches to reduce the solids content by dilution as soon as carbohydrate consumption rate during fermentation decreases as signified by foam collapse.
Furthermore, DE-A 44 01 694 describes a batch process for the preparation of filtered wort that uses recovered filter water to achieve enhanced concentration of the wort. The stated aim is to arrange the separation process with the mash filter in such a way that a final concentration, prior to concentration by evaporation, of more than 19 GG-% is achieved. Furthermore, it is observed in the German patent application that preferably the primary wort concentration is between 23 GG-% and 25 GG-%.